A cellulose ether as a final product is usually obtained by comprising the steps of adsorbing alkali metal hydroxide onto cellulose to form alkali cellulose, reacting the alkali cellulose with an alkylating agent or a hydroxylating agent, optionally neutralizing in an addition of acid, and then washing, dehydrating, drying, and grinding.
A wet cellulose ether changes from a soft muddy form to a hard cake form, depending on the dehydration degree in the dehydration step, and has adhesiveness and cohesiveness. For drying of such a muddy or cake-like material, a conductive heat-transfer type agitated trough dryer excellent in thermal efficiency or a convective heat-transfer type pneumatic dryer effective for drying of an adhesive material as shown in JP 2010-132920A is usually employed.